Distance and Displacement
Speed and Velocity
Acceleration
Graphing Motion
Labs
100
Finish these statements: "Displacement is the difference between …." "Distance is …."
…the final position and the initial position …the length of the total path traveled
100
What does speed mean? Units? Vector/Scalar?
Speed is the distance per time units are m/s and it is a scalar and NOT a vector
100
What does acceleration mean? units? Vector?
Acceleration is the change in velocity per time units of m/s2 Yes, acceleration is a vector
100
What does the slope represent on a 1. position vs. time graph? 2. velocity vs. time graph?
1. velocity 2. acceleration
100
You are supplied with a set of photogates. How could you measure the maximum speed of a ball fired upwards? 1. With 1 photogate? 2. With 2 photogates?
1. Measure the diameter and the time it broke the light. Do this near the launch point and divide the diameter by the time difference. 2. Measure the distance between photogates. Let the ball break both lights. Divide the distance between the photogates by the time difference
200
What does it mean for a variable to be a vector?
It means that variable has both size and direction
200
What does velocity mean? Units? Vector/Scalar?
Velocity is the displacement per time units are m/s and it is a vector
200
A train can move East or West on a track. What are the two things the train can do in order to have negative acceleration?
Move West and speed up or move East and slow down
200
On a velocity vs. time graph, how do you know if the object is slowing down?
The curve/line moves towards horizontal axis (either from above or from below)
200
Which one of the following are NOT possible "experimental errors" and should NOT be listed in a lab report a. air resistance b. forgetting to divide by 2 in calculations c. using the wrong side of meterstick d. the motion detector was slightly angled away from the direction of motion of object
a and b
300
Why might the distance be difference from the displacement? Give one example and explain.
The sign could be different: If the path is left or down displacement could be negative Or the magnitude could be different: If the object changes direction
300
What is the difference between average and instantaneous velocity? Give at least one example where they would be different and explain.
Instantaneous velocity is the velocity at a particular instant, Average velocity is the displacement per time over a time interval If an object changes direction, the sign and magnitude could be different
300
Is there a difference between negative acceleration, and decreasing acceleration? If so, give a situation where there is one but not the other.
Yes there is a difference. Negative acceleration means the acceleration points left or down ("adding velocity left or down"). But decreasing acceleration means the value of the acceleration goes down.
300
What does the area underneath the curve represent on a 1. Velocity vs. time graph 2. Acceleration vs. time graph
1. Displacement 2. the change in velocity (not just velocity!)
300
What does "independent variable" and "dependent variable" mean? Give one example.
Independent variable is the variable you change and choose the value of Dependent variable is the variable you measure that might change based on your changing of independent variable
400
While standing on top of a 35m tall building, you throw a 3kg teddy bear upwards with a speed of 12m/s. The stuffed animal flies 7m above the top of the building and lands on the ground. What was the distance and displacement of the teddy bear for the entire trip?
Distance: 49m Displacement: -35m
400
A car drives 10m/s East for 2 minutes, then instantly turns around and drives 30m/s West for 1 minute. 1. What was the average speed for the entire trip? 2. What was the instantaneous velocity at a time 130 seconds after starting the trip?
Average Speed = 3000m/180s = 16.7 m/s Instantaneous Velocity at 130 seconds = -30m/s
400
A 3,400kg car is moving 23m/s West and 10 seconds later the car is moving 17m/s East. What was the magnitude and direction of the average acceleration of the car?
Magnitude: 4m/s2 Direction: East (+)
400
Draw a position vs. time graph where the object 1. starts with negative velocity 2. then slows down to a stop 3. then speeds up to a constant speed 4. then keeps traveling with that constant speed
Graph should start with negative slope (from anywhere) then get less steep and bottom out then get more steep (either up or down) then continue with that steepness (should NOT go level)
400
Give one possible likely error that would occur when using the following number of photogates to measure the instantaneous speed of a dropped ball at the "half way down point". Also give the effect the error has on the size of the measured speed. 1. With 1 photo gate at the half way down point 2. With 2 photogates (one at halfway down and one 1/4 of the way down)
1. Ball did not pass straight through the photo gate which means the speed would be too large since time difference would be too small (or diameter would be too large) 2. The instantaneous speed is getting larger so you would measure an average speed that is less than the instantaneous speed at halfway
500
While standing on the street next to a building that is 32m tall, you throw a 2kg rubber duck upwards with a speed of 27m/s. The rubber duck flies 6m past the top of the building and falls back down landing on top of the building. What was the distance and displacement of the rubber duck for the entire trip?
Distance: 44m Displacement: 32m
500
A train moves at 50m/s South for 2500m, then stops for 10 seconds, then moves at 20m/s North for 2 minutes. What was the average speed of the train for the entire trip? What was the average velocity of the train for the entire trip?
Average Speed = 27.2m/s Average Velocity = -0.56m/s
500
A 1,200kg elevator is moving 16m/s downwards when it passes the 11th floor. Immediately after passing the 11th floor, the elevator starts to slow down with constant deceleration and takes 8 seconds to come to rest 32m lower at the 7th floor. What was the magnitude and direction of the acceleration of the elevator?
Magnitude: 2m/s2 Direction: Upwards (+)
500
Draw a velocity vs. time graph where the object 1. starts with negative velocity 2. then slows down to a stop 3. then speeds up to a constant speed 4. then keeps traveling with that constant speed
Graph should start below horizontal axis then move to horizontal axis then move above (or below horizontal axis) then should be a horizontal line
500
You are provided with unlimited photogates and metersticks. Describe a lab procedure you could use to measure the acceleration of a ball falling down.
Use the single photogates to measure instantaneous velocities. Then take the difference in those instantaneous velocities and divide by the time between them to find acceleration during each interval.
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